This program, presently in its 20th year of funding, supports training of predoctoral (5) and postdoctoral (3) fellows in the biology of pathogenic microorganisms and their interaction with the human host. Preceptors on this training grant work on bacteria, viruses, and parasites that cause important human diseases and on the host immune response against these infectious agents. The principal focus is on the interaction of these microbes with the host and the processes whereby these interactions lead to disease. A central tenet for training is that trainees require exposure to broad, interdisciplinary areas of science to investigate the complex interactions between microbes and their hosts. Trainees are provided with conceptual and experimental foundations in microbiology, biochemistry, molecular biology, genetics, cell biology, genomics, proteomics, chemical biology, and computational biology. Faculty preceptors (28 at present) derive from 5 academic departments, 4 research institutes, and 3 clinical departments, providing a broad base of interdisciplinary research expertise. Preceptors in this program are highly collaborative and interactive, affording trainees exposure to a wide array of methods and approaches to problems in pathogenic microbiology. Trainees are selected by a committee of faculty preceptors from a highly competitive pool of applicants using clearly defined criteria. Successful applicants report research findings at least annually at a department seminar and receive feedback and critiques from multiple faculty members. The program tracks the progress of trainees both during and after their support by the training fellowship. Mentors and trainees provide an annual report describing progress on the research project and on overall professional advancement. An important new component of training entails a yearlong series of Career Development Meetings that allow both pre- and postdoctoral trainees to learn about a variety of career options in science and to develop essential networks of contacts for entering such disciplines. A Steering Committee evaluates the success of the program on an ongoing basis and suggests alterations or improvements as necessary. The program has been very successful in attracting and supporting women and minorities and continues to set a high priority on training members of groups that are traditionally underrepresented in science. Program support is provided by the institution in the form of administrative positions and fellowships for predoctoral students during the early years of their graduate program and by an additional trainee stipend. This training program has evolved significantly since its initiation, adding a large number of new preceptors and greatly increasing the representation of cutting edge methodologies and novel approaches relevant to understanding how microorganisms cause disease.